Interleukin 17A plays a role in lipopolysaccharide/D-galactosamine-induced fulminant hepatic injury in mice.

Abstract

Lipopolysaccharide/d-galactosamine (LPS/GalN)-induced hepatic injury is an experimental model of fulminant hepatic failure in which tumor necrosis factor alpha (TNF-α) plays a pivotal role. Moreover, it was reported from our laboratory that interleukin (IL) 17A enhanced production of TNF-α by the Kupffer cell. The purpose of this study was to determine the role of IL-17A in LPS/GalN-induced hepatic injury in mice. LPS/GalN was injected into three mouse models: wild-type (WT) mice, IL-17A knockout (KO) mice, or IL-17A KO mice treated with recombinant mouse (rm) IL-17A homodimer (KO + rmIL-17A). Survival was assessed for 24 h after LPS/GalN injection, and histopathologic findings were evaluated at various time points after LPS/GalN injection for neutrophil and apoptosis markers. After LPS/GalN injection, expression of the inflammatory mediators TNF-α, IL-6, monocyte chemotactic protein 1, IL-17A, high-mobility group box 1, and soluble intercellular adhesion molecule 1 was assessed in serum by enzyme-linked immunosorbent assay. Survival was higher in KO mice compared with WT mice after LPS/GalN injection. However, in KO + rmIL-17A mice, mortality was not significantly different compared to the other groups. Neutrophil infiltration and apoptosis were significantly greater in WT mice than KO mice. Furthermore, serum alanine aminotransferase, serum TNF-α, monocyte chemotactic protein 1, IL-17A, high-mobility group box 1, and soluble intercellular adhesion molecule 1 levels were also significantly greater in WT mice than KO mice. In KO + rmIL-17A mice, these levels were similar to those in WT mice. IL-17A is a key regulator in hepatic injury caused by neutrophil-induced inflammatory responses after LPS/GalN injection.